The present invention relates to a power train suitable for use in an amphibious vehicle capable of travel on land and water, particularly to a power train in which a conventional in-line automotive engine and transmission arrangement is adapted to drive at least some of the wheels and a marine propulsion means of an amphibious vehicle. The invention also relates to an amphibious vehicle having such a power train.
In a known automotive power train arrangement, an engine having a crankshaft is positioned such that the crankshaft is in-line with the longitudinal axis of the vehicle. The engine drives a transmission which is arranged in line with and behind the engine. Often, the transmission has an integral differential which is connected by axle shafts to drive a pair of road wheels of the vehicle. This arrangement is commonly known as a transaxle drive and has been employed in front engine, rear engine and mid engine power train layouts.
The in-line power train, and in particular the transaxle front wheel drive arrangement is currently used by several large car manufacturers in the production of larger private passenger vehicles and is therefore produced in relatively high volumes, which makes the arrangement most procurable for use in an amphibious vehicle. In choosing a power train for a specialized low volume production vehicle, such as an amphibious vehicle, availability is an important factor.
It is an object of the present invention to provide a power train for an amphibious vehicle, in which a conventional in-line engine and transmission are utilized and adapted. It is a further object of the invention to provide an amphibious vehicle having such a power train.
In accordance with a first aspect of the invention, there is provided a power train for an amphibious vehicle, which power train comprises an engine adapted for mounting in the vehicle such that a crankshaft of the engine is substantially in alignment with a longitudinal axis of the vehicle, a transmission, and a power take off positioned in the drive line between the engine and the transmission, characterized in that the power take off is adapted to drive at least one marine propulsion unit located at the rear of the amphibious vehicle by means of a shaft which runs alongside the transmission.
In a preferred embodiment, a transfer drive is provided between the engine and the transmission, the transfer drive being adapted to transfer drive from the crankshaft of the engine to the transmission and to a drive shaft for the marine propulsion means, the drive shaft for the marine propulsion means being in axial alignment, or substantially so, with the crankshaft of the engine, and the transmission being offset relative to the crankshaft. The transfer drive may comprise a driving sprocket offset arranged for rotation with the crankshaft of the engine and a driven sprocket offset from the crankshaft, the driving and driven sprockets being drivingly interconnected by a toothed belt or chain. The driving sprocket may be mounted to a first shaft which is connected to the crankshaft of the engine, the first shaft being adapted to drive the drive shaft for the marine propulsion unit. The first shaft may be connected to the drive shaft for the marine propulsion unit by a decoupler. In a preferred arrangement, the driven sprocket is arranged to drive a second shaft which provides an input to the transmission. The second shaft may be connected to an input shaft of the transmission by a drive coupling unit such as a fiction clutch or a fluid coupling.
In an alternative preferred embodiment, the transmission is adapted to be mounted such that it is substantially in axial alignment with the axis of the crankshaft with the center line of the at least one marine propulsion unit being located parallel to and offset from the longitudinal axis of the vehicle. In such an arrangement, the power take off may be adapted to drive two marine propulsion units located at the rear of the amphibious vehicle, the respective center lines of the marine propulsion units being located parallel to and offset from the longitudinal axis of the amphibious vehicle on opposite sides thereof. The power take off may be adapted to drive the two marine propulsion units by means of shafts which run along opposite sides of the transmission.
Preferably, the engine and transmission are adapted to be positioned towards the front of the amphibious vehicle and to provide drive to at least the front wheels of the vehicle.
Alternatively, the engine and transmission are adapted to be positioned towards the rear of the vehicle and to provide drive to at least the rear wheels of the vehicle.
In a further alternative embodiment, the engine is adapted to be positioned towards the front of the vehicle and the transmission is adapted to be positioned towards the rear of the vehicle and to provide drive to at least the rear wheels of the vehicle.
Preferably, the transmission is a transaxle unit integral gearbox and differential. Alternatively, the transmission may have an output located to one side thereof and which drives a differential positioned adjacent a sump of the engine.
A further power take off may be provided such that the power train can provide drive to both the front and the rear wheels of the vehicle.
Preferably, the shaft or shafts which run alongside the transmission are adapted to be mounted in alignment with or parallel to the longitudinal axis of the vehicle.
In accordance with a second aspect of the invention, there is provided an amphibious vehicle, characterized in that it comprises a power train in accordance with the first aspect of the invention.